Nitrogen Cycling in the Upwelling Waters of the Equatorial Pacific Region

赤道太平洋沃茨营养物质的上涌增强了 浮游生物生物量和初级生产量， 可能占全球新闻的很大一部分， 生产 硝酸盐持续存在于a区的透光层中 在上升流轴南北几百公里处， 已经提出了几个假设来解释明显的 浮游植物无法充分利用它。这个项目 假设放牧控制浮游植物生物量， 营养物质的循环提供了大量的浮游植物 氮素需要量 这项研究将利用已应用的新技术 在过去的几年里在马尾藻海和JGOFS北部 大西洋开花实验，以测试放牧/再生 这是美国JGOFS赤道太平洋计划的一部分。 这一假设意味着特定的模式和分布 含氮营养物及其利用和再生，以及 营养物和悬浮物中天然氮同位素丰度， 沉降颗粒物质 该项目是与 Jim McCarthy（9022411），由两个主要组成部分组成：1） 高精度营养浓度测量（纳摩尔 2）高灵敏度（如有必要）和高空间分辨率; 水平和高灵敏度示踪剂研究其生物 吸收和转化。这项研究的结果将 构成对“新”的相对重要性的评估， “再生”氮在赤道太平洋地区。的 将确定调节生产的主要机制， 以及“新”生产对颗粒的贡献程度 将评估通量和碳固存。

The upwelling of nutrients in Equatorial Pacific waters enhances plankton biomass and primary production over a large area and may account for a significant fraction of the global new production. Nitrate persists in the euphotic zone in an area a few hundred kilometers north and south of the upwelling axis and several hypotheses have been advanced to account for the apparent inability of the phytoplankton to fully utilize it. This project hypothesizes that grazing controls phytoplankton biomass and that recycling of nutrients provides much of the phytoplankton nitrogen requirement. This study will utilize new techniques which have been applied over the last few years in the Sargasso Sea and the JGOFS North Atlantic Bloom Experiment to test the grazing/regeneration hypothesis as part of the U.S JGOFS Equatorial Pacific program. This hypothesis implies specific patterns and distributions of nitrogenous nutrients, their utilization and regeneration, and natural N isotope abundance in nutrients and suspended and sinking particulate material. This project is collaborative with Jim McCarthy (9022411) and consists of two major components: 1) nutrient concentration measurements of high precision (nanomolar sensitivity where necessary) and high spatial resolution; 2) low level and high sensitivity tracer studies of their biological uptake and transformations. The results of this study will constitute an assessment of the relative importance of "new" and "regenerated" nitrogen in the Equatorial Pacific region. The principal mechanisms regulating production will be identified, and the extent to which "new" production contributes to particle flux and carbon sequestration will be assessed.